The acl_calc_mask() function calculates and sets
the permissions associated with the ACL_MASK ACL entry of the ACL referred to
by acl_p. The value of the new permissions is
the union of the permissions granted by all entries of tag type ACL_GROUP,
ACL_GROUP_OBJ, or ACL_USER. If the ACL referred to by
acl_p already contains an ACL_MASK entry, its
permissions are overwritten; if it does not contain an ACL_MASK entry, one is
added.

If the ACL referred to by acl_p does not
contain enough space for the new ACL entry, then additional working storage
may be allocated. If the working storage cannot be increased in the current
location, then it may be relocated and the previous working storage is
released and a pointer to the new working storage is returned via
acl_p.

The order of existing entries in the ACL is undefined after this function.

Any existing ACL entry descriptors that refer to entries in the ACL continue to
refer to those entries. Any existing ACL pointers that refer to the ACL
referred to by acl_p continue to refer to the
ACL.

RETURN
VALUE

The acl_calc_mask() function returns the
value 0 if successful; otherwise the value -1 is returned and
the global variable errno is set to indicate
the error.

ERRORS

If any of the following conditions occur, the
acl_calc_mask() function returns
-1 and sets errno to
the corresponding value:

[EINVAL]

The argument acl is not a
valid pointer to an ACL.

[ENOMEM]

The acl_calc_mask() function
is unable to allocate the memory required for an ACL_MASK ACL entry.